In the past various types of resilient needle valve and plugs have been provided for receiving a needle valve or probe from a low pressure region to sense a high pressure region such as on a pipe line. The resilient valves in the past have been designed to prevent leakage but it has been a continuous problem to provide a device which is low in cost, simple to use and rugged in construction. Further, there has been a problem in the use of a test probe, such as for temperature sensing through a thermometer, to prevent leakage after the thermometer has been left in the resilient valve core for a period of time due to set of the valve core. On removal, the rubber valve may not return to its original position rapidly and a spurt of hot fluid or sometimes dangerous fluid may escape with obvious hazard to personnel.
In my U.S. Pat. No. 3,797,317, a test plug having separately moveable valve cores is provided. While this test plug has provided a substantial advance in the art and has worked quite efficiently, it remains a problem to provide a fast acting closure of the valves upon removal of the test probe. It has further been a problem and nuisance in the removal of the cap for the test plug to prevent misplacement. Through inadvertence, such caps which are removed when the test probe is removed from the test plug, are quite often lost or misplaced.